<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>动画</title>
		<style type="text/css">
			.box{
				font-size: 40px;
				align-items: center;
				border:5px solid magenta;
				background-color: blueviolet;
				animation:ppt 10s infinite linear 2s;
				
			}
			@keyframes ppt{
				0%,30%{
					width: 800px;
					height: 600px;
					background-color: brown;
				}
				40%,50%{
					
				}
			}
		</style>
	</head>
	<body>
		<div class="box"></div>
	</body>
</html>